RDMA/cm: Use specific keyword to check define

There is a specific define keyword to check if define exists or not,
let's use it instead of open-coded variant.

Link: https://lore.kernel.org/r/20191020071559.9743-3-leon@kernel.orgSigned-off-by: NLeon Romanovsky <leonro@mellanox.com>
Reviewed-by: NJason Gunthorpe <jgg@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/cm_msgs.h

@@ -31,7 +31,7 @@
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS THE
  * SOFTWARE.
  */
-#if !defined(CM_MSGS_H)
+#ifndef CM_MSGS_H
 #define CM_MSGS_H
 
 #include <rdma/ib_mad.h>

include/rdma/ib_cm.h

@@ -32,7 +32,7 @@
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-#if !defined(IB_CM_H)
+#ifndef IB_CM_H
 #define IB_CM_H
 
 #include <rdma/ib_mad.h>